Deobfuscate and document purpose of misunderstood code in traverseBlocks()

(cherry picked from commit 335c33b109)

.github/workflows/codeql-analysis.yml

@@ -1,71 +0,0 @@
-# For most projects, this workflow file will not need changing; you simply need
-# to commit it to your repository.
-#
-# You may wish to alter this file to override the set of languages analyzed,
-# or to provide custom queries or build logic.
-#
-# ******** NOTE ********
-# We have attempted to detect the languages in your repository. Please check
-# the `language` matrix defined below to confirm you have the correct set of
-# supported CodeQL languages.
-#
-name: "CodeQL"
-
-on:
-  push:
-    branches: [ master ]
-  pull_request:
-    # The branches below must be a subset of the branches above
-    branches: [ master ]
-  schedule:
-    - cron: '30 15 * * 2'
-
-jobs:
-  analyze:
-    name: Analyze
-    runs-on: ubuntu-latest
-    permissions:
-      actions: read
-      contents: read
-      security-events: write
-
-    strategy:
-      fail-fast: false
-      matrix:
-        language: [ 'java' ]
-        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python' ]
-        # Learn more:
-        # https://docs.github.com/en/free-pro-team@latest/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#changing-the-languages-that-are-analyzed
-
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v2
-
-      # Initializes the CodeQL tools for scanning.
-      - name: Initialize CodeQL
-        uses: github/codeql-action/init@v1
-        with:
-          languages: ${{ matrix.language }}
-          # If you wish to specify custom queries, you can do so here or in a config file.
-          # By default, queries listed here will override any specified in a config file.
-          # Prefix the list here with "+" to use these queries and those in the config file.
-          # queries: ./path/to/local/query, your-org/your-repo/queries@main
-
-      # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
-      # If this step fails, then you should remove it and run the build manually (see below)
-      - name: Autobuild
-        uses: github/codeql-action/autobuild@v1
-
-      # ℹ️ Command-line programs to run using the OS shell.
-      # 📚 https://git.io/JvXDl
-
-      # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
-      #    and modify them (or add more) to build your code if your project
-      #    uses a compiled language
-
-      #- run: |
-      #   make bootstrap
-      #   make release
-
-      - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v1

.github/workflows/gradle-publish.yml

@@ -1,38 +0,0 @@
-# This workflow uses actions that are not certified by GitHub.
-# They are provided by a third-party and are governed by
-# separate terms of service, privacy policy, and support
-# documentation.
-# This workflow will build a package using Gradle and then publish it to GitHub packages when a release is created
-# For more information see: https://github.com/actions/setup-java/blob/main/docs/advanced-usage.md#Publishing-using-gradle
-
-name: Gradle Package
-
-on:
-  [push, workflow_dispatch]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      packages: write
-
-    steps:
-    - uses: actions/checkout@v3
-    - name: Set up JDK 17
-      uses: actions/setup-java@v3
-      with:
-        java-version: '17'
-        distribution: 'temurin'
-        server-id: github # Value of the distributionManagement/repository/id field of the pom.xml
-        settings-path: ${{ github.workspace }} # location for the settings.xml file
-
-    - name: Build with Gradle
-      uses: gradle/gradle-build-action@67421db6bd0bf253fb4bd25b31ebb98943c375e1
-      with:
-        arguments: build
-    - name: Upload a Build Artifact
-      uses: actions/upload-artifact@v3.1.0
-      with:
-        path: /home/runner/work/Grim/Grim/build/libs/**.jar

.github/workflows/gradle.yml

@@ -0,0 +1,95 @@
+# This workflow uses actions that are not certified by GitHub.
+# They are provided by a third-party and are governed by
+# separate terms of service, privacy policy, and support
+# documentation.
+# This workflow will build a Java project with Gradle and cache/restore any dependencies to improve the workflow execution time
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-java-with-gradle
+
+name: Java CI with Gradle
+
+on:
+  push:
+    branches: [ "2.0" ]
+  pull_request:
+    branches: [ "2.0" ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      # Configure Gradle for optimal use in GitHub Actions, including caching of downloaded dependencies.
+      # See: https://github.com/gradle/actions/blob/main/setup-gradle/README.md
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@dbbdc275be76ac10734476cc723d82dfe7ec6eda
+
+      - name: Build with Gradle Wrapper
+        run: ./gradlew build
+
+      - name: Get current datetime
+        id: datetime
+        run: echo "datetime=$(date +'%Y-%m-%d-%H%M%S')" >> $GITHUB_OUTPUT
+
+      - name: Delete previous dev release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          previous_release_id=$(curl -s -H "Authorization: token $GITHUB_TOKEN" \
+            "https://api.github.com/repos/${{ github.repository }}/releases/tags/dev" | jq -r .id)
+          if [ "$previous_release_id" != "null" ]; then
+            curl -X DELETE -H "Authorization: token $GITHUB_TOKEN" \
+              "https://api.github.com/repos/${{ github.repository }}/releases/$previous_release_id"
+            git push --delete origin dev || true
+          fi
+      - name: Create new dev release
+        id: create_release
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          tag_name: dev
+          release_name: Dev Build ${{ steps.datetime.outputs.datetime }}
+          body: |
+            This is an automated dev build of the master branch.
+            Build date: ${{ steps.datetime.outputs.datetime }}
+          draft: false
+          prerelease: true
+
+      - name: Find JAR file
+        id: find_jar
+        run: |
+          JAR_PATH=$(find ./build/libs -name "*.jar" | head -n 1)
+          echo "jar_path=$JAR_PATH" >> $GITHUB_OUTPUT
+          echo "jar_name=$(basename $JAR_PATH)" >> $GITHUB_OUTPUT
+      - name: Upload artifact
+        uses: actions/upload-release-asset@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          upload_url: ${{ steps.create_release.outputs.upload_url }}
+          asset_path: ${{ steps.find_jar.outputs.jar_path }}
+          asset_name: GrimAC-${{ steps.datetime.outputs.datetime }}-dev.jar
+          asset_content_type: application/java-archive
+
+  dependency-submission:
+
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'

src/main/java/ac/grim/grimac/checks/impl/combat/Reach.java

@@ -15,12 +15,16 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 package ac.grim.grimac.checks.impl.combat;
 
+import ac.grim.grimac.GrimAPI;
 import ac.grim.grimac.checks.Check;
 import ac.grim.grimac.checks.CheckData;
 import ac.grim.grimac.checks.type.PacketCheck;
 import ac.grim.grimac.player.GrimPlayer;
 import ac.grim.grimac.utils.collisions.datatypes.SimpleCollisionBox;
+import ac.grim.grimac.utils.data.HitData;
+import ac.grim.grimac.utils.data.Pair;
 import ac.grim.grimac.utils.data.packetentity.PacketEntity;
+import ac.grim.grimac.utils.nmsutil.BlockRayTrace;
 import ac.grim.grimac.utils.data.packetentity.dragon.PacketEntityEnderDragonPart;
 import ac.grim.grimac.utils.nmsutil.ReachUtils;
 import com.github.retrooper.packetevents.event.PacketReceiveEvent;
@@ -30,12 +34,22 @@ import com.github.retrooper.packetevents.protocol.entity.type.EntityTypes;
 import com.github.retrooper.packetevents.protocol.packettype.PacketType;
 import com.github.retrooper.packetevents.protocol.player.ClientVersion;
 import com.github.retrooper.packetevents.protocol.player.GameMode;
+import com.github.retrooper.packetevents.protocol.world.states.WrappedBlockState;
 import com.github.retrooper.packetevents.util.Vector3d;
+import com.github.retrooper.packetevents.util.Vector3i;
 import com.github.retrooper.packetevents.wrapper.play.client.WrapperPlayClientInteractEntity;
 import com.github.retrooper.packetevents.wrapper.play.client.WrapperPlayClientPlayerFlying;
 import org.bukkit.util.Vector;
+import org.jetbrains.annotations.Nullable;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 // You may not copy the check unless you are licensed under GPL
 @CheckData(name = "Reach", configName = "Reach", setback = 10)
@@ -43,6 +57,9 @@ public class Reach extends Check implements PacketCheck {
     // Only one flag per reach attack, per entity, per tick.
     // We store position because lastX isn't reliable on teleports.
     private final Map<Integer, Vector3d> playerAttackQueue = new HashMap<>();
+    // Used to prevent falses in the wall hit check
+    private final Set<Vector3i> blocksChangedThisTick = new HashSet<>();
+
     private static final List<EntityType> blacklisted = Arrays.asList(
             EntityTypes.BOAT,
             EntityTypes.CHEST_BOAT,
@@ -105,10 +122,11 @@ public class Reach extends Check implements PacketCheck {
         }
 
         // If the player set their look, or we know they have a new tick
-        if (WrapperPlayClientPlayerFlying.isFlying(event.getPacketType()) ||
+        final boolean isFlying = WrapperPlayClientPlayerFlying.isFlying(event.getPacketType());
+        if (isFlying ||
                 event.getPacketType() == PacketType.Play.Client.PONG ||
                 event.getPacketType() == PacketType.Play.Client.WINDOW_CONFIRMATION) {
-            tickBetterReachCheckWithAngle();
+            tickBetterReachCheckWithAngle(isFlying);
         }
     }
 
@@ -140,7 +158,7 @@ public class Reach extends Check implements PacketCheck {
         }
     }
 
-    private void tickBetterReachCheckWithAngle() {
+    private void tickBetterReachCheckWithAngle(boolean isFlying) {
         for (Map.Entry<Integer, Vector3d> attack : playerAttackQueue.entrySet()) {
             PacketEntity reachEntity = player.compensatedEntities.entityMap.get(attack.getKey().intValue());
             if (reachEntity != null) {
@@ -155,6 +173,9 @@ public class Reach extends Check implements PacketCheck {
             }
         }
         playerAttackQueue.clear();
+        // We can't use transactions for this because of this problem:
+        // transaction -> block changed applied -> 2nd transaction -> list cleared -> attack packet -> flying -> reach block hit checked, falses
+        if (isFlying) blocksChangedThisTick.clear();
     }
 
     private String checkReach(PacketEntity reachEntity, Vector3d from, boolean isPrediction) {
@@ -219,9 +240,26 @@ public class Reach extends Check implements PacketCheck {
             }
         }
 
+        final boolean experimentalChecks = true; //GrimAPI.INSTANCE.getConfigManager().isExperimentalChecks(); // TODO fix for undraft
+        HitData foundHitData = null;
+        // If the entity is within range of the player (we'll flag anyway if not, so no point checking blocks in this case)
+        // Ignore when could be hitting through a moving shulker, piston blocks. They are just too glitchy/uncertain to check.
+        if (experimentalChecks && minDistance <= 3 && !player.compensatedWorld.isNearHardEntity(player.boundingBox.copy().expand(4))) {
+            final @Nullable Pair<Double, HitData> targetBlock = getTargetBlock(player, possibleLookDirs, from, minDistance);
+            // And if the target block is closer to the player than the entity box, they should hit the block instead
+            // So, this hit is invalid.
+            if (targetBlock != null && targetBlock.getFirst() < (minDistance * minDistance)) { // targetBlock is squared
+                minDistance = Double.MIN_VALUE;
+                foundHitData = targetBlock.getSecond();
+            }
+        }
+
         // if the entity is not exempt and the entity is alive
         if ((!blacklisted.contains(reachEntity.getType()) && reachEntity.isLivingEntity()) || reachEntity.getType() == EntityTypes.END_CRYSTAL) {
-            if (minDistance == Double.MAX_VALUE) {
+            if (minDistance == Double.MIN_VALUE && foundHitData != null) {
+                cancelBuffer = 1;
+                return "Hit block block=" + foundHitData.getState().getType().getName();
+            } else if (minDistance == Double.MAX_VALUE) {
                 cancelBuffer = 1;
                 return "Missed hitbox";
             } else if (minDistance > player.compensatedEntities.getSelf().getAttributeValue(Attributes.PLAYER_ENTITY_INTERACTION_RANGE)) {
@@ -235,6 +273,45 @@ public class Reach extends Check implements PacketCheck {
         return null;
     }
 
+    public void handleBlockChange(Vector3i vector3i, WrappedBlockState state) {
+        if (blocksChangedThisTick.size() >= 40) return; // Don't let players freeze movement packets to grow this
+        // Only do this for nearby blocks
+        if (new Vector(vector3i.x, vector3i.y, vector3i.z).distanceSquared(new Vector(player.x, player.y, player.z)) > 6) return;
+        // Only do this if the state really had any world impact
+        if (state.equals(player.compensatedWorld.getWrappedBlockStateAt(vector3i))) return;
+        blocksChangedThisTick.add(vector3i);
+    }
+
+    // Returns a pair so we can check the block type in the flag
+    @Nullable
+    private Pair<Double, HitData> getTargetBlock(GrimPlayer player, List<Vector> possibleLookDirs, Vector3d from, double minDistance) {
+        // Check every possible look direction and every possible eye height
+        // IF *NONE* of them allow the player to hit the entity, this is an invalid hit
+        HitData bestHitData = null;
+        double min = Double.MAX_VALUE;
+        for (Vector lookVec : possibleLookDirs) {
+            for (double eye : player.getPossibleEyeHeights()) {
+                Vector eyes = new Vector(from.getX(), from.getY() + eye, from.getZ());
+                final double reach = player.compensatedEntities.getSelf().getAttributeValue(Attributes.PLAYER_BLOCK_INTERACTION_RANGE);
+                final HitData hitResult = BlockRayTrace.getNearestReachHitResult(player, eyes, lookVec, minDistance, reach);
+                if (hitResult == null) {
+                    return null;
+                }
+
+                final double distance = eyes.distanceSquared(hitResult.getBlockHitLocation());
+                // Block changes are uncertain, can't check this tick
+                if (distance < (minDistance * minDistance) && blocksChangedThisTick.contains(hitResult.getPosition())) {
+                    return null;
+                }
+
+                bestHitData = hitResult;
+                min = Math.min(min, distance);
+            }
+        }
+
+        return bestHitData == null ? null : Pair.of(min, bestHitData);
+    }
+
     @Override
     public void reload() {
         super.reload();

src/main/java/ac/grim/grimac/events/packets/CheckManagerListener.java

@@ -14,7 +14,6 @@ import ac.grim.grimac.utils.collisions.datatypes.SimpleCollisionBox;
 import ac.grim.grimac.utils.data.*;
 import ac.grim.grimac.utils.inventory.Inventory;
 import ac.grim.grimac.utils.latency.CompensatedWorld;
-import ac.grim.grimac.utils.math.GrimMath;
 import ac.grim.grimac.utils.math.VectorUtils;
 import ac.grim.grimac.utils.nmsutil.*;
 import com.github.retrooper.packetevents.PacketEvents;
@@ -47,11 +46,9 @@ import com.github.retrooper.packetevents.wrapper.play.client.*;
 import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerAcknowledgeBlockChanges;
 import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerSetSlot;
 import io.github.retrooper.packetevents.util.SpigotConversionUtil;
-import org.bukkit.util.Vector;
-
 import java.util.ArrayList;
 import java.util.List;
-import java.util.function.BiFunction;
+import org.bukkit.util.Vector;
 
 public class CheckManagerListener extends PacketListenerAbstract {
 
@@ -59,79 +56,8 @@ public class CheckManagerListener extends PacketListenerAbstract {
         super(PacketListenerPriority.LOW);
     }
 
-    // Copied from MCP...
-    // Returns null if there isn't anything.
-    //
-    // I do have to admit that I'm starting to like bifunctions/new java 8 things more than I originally did.
-    // although I still don't understand Mojang's obsession with streams in some of the hottest methods... that kills performance
-    public static HitData traverseBlocks(GrimPlayer player, Vector3d start, Vector3d end, BiFunction<WrappedBlockState, Vector3i, HitData> predicate) {
-        // I guess go back by the collision epsilon?
-        double endX = GrimMath.lerp(-1.0E-7D, end.x, start.x);
-        double endY = GrimMath.lerp(-1.0E-7D, end.y, start.y);
-        double endZ = GrimMath.lerp(-1.0E-7D, end.z, start.z);
-        double startX = GrimMath.lerp(-1.0E-7D, start.x, end.x);
-        double startY = GrimMath.lerp(-1.0E-7D, start.y, end.y);
-        double startZ = GrimMath.lerp(-1.0E-7D, start.z, end.z);
-        int floorStartX = GrimMath.floor(startX);
-        int floorStartY = GrimMath.floor(startY);
-        int floorStartZ = GrimMath.floor(startZ);
-
-
-        if (start.equals(end)) return null;
-
-        WrappedBlockState state = player.compensatedWorld.getWrappedBlockStateAt(floorStartX, floorStartY, floorStartZ);
-        HitData apply = predicate.apply(state, new Vector3i(floorStartX, floorStartY, floorStartZ));
-
-        if (apply != null) {
-            return apply;
-        }
-
-        double xDiff = endX - startX;
-        double yDiff = endY - startY;
-        double zDiff = endZ - startZ;
-        double xSign = Math.signum(xDiff);
-        double ySign = Math.signum(yDiff);
-        double zSign = Math.signum(zDiff);
-
-        double posXInverse = xSign == 0 ? Double.MAX_VALUE : xSign / xDiff;
-        double posYInverse = ySign == 0 ? Double.MAX_VALUE : ySign / yDiff;
-        double posZInverse = zSign == 0 ? Double.MAX_VALUE : zSign / zDiff;
-
-        double d12 = posXInverse * (xSign > 0 ? 1.0D - GrimMath.frac(startX) : GrimMath.frac(startX));
-        double d13 = posYInverse * (ySign > 0 ? 1.0D - GrimMath.frac(startY) : GrimMath.frac(startY));
-        double d14 = posZInverse * (zSign > 0 ? 1.0D - GrimMath.frac(startZ) : GrimMath.frac(startZ));
-
-        // Can't figure out what this code does currently
-        while (d12 <= 1.0D || d13 <= 1.0D || d14 <= 1.0D) {
-            if (d12 < d13) {
-                if (d12 < d14) {
-                    floorStartX += xSign;
-                    d12 += posXInverse;
-                } else {
-                    floorStartZ += zSign;
-                    d14 += posZInverse;
-                }
-            } else if (d13 < d14) {
-                floorStartY += ySign;
-                d13 += posYInverse;
-            } else {
-                floorStartZ += zSign;
-                d14 += posZInverse;
-            }
-
-            state = player.compensatedWorld.getWrappedBlockStateAt(floorStartX, floorStartY, floorStartZ);
-            apply = predicate.apply(state, new Vector3i(floorStartX, floorStartY, floorStartZ));
-
-            if (apply != null) {
-                return apply;
-            }
-        }
-
-        return null;
-    }
-
     private static void placeWaterLavaSnowBucket(GrimPlayer player, ItemStack held, StateType toPlace, InteractionHand hand) {
-        HitData data = getNearestHitResult(player, StateTypes.AIR, false);
+        HitData data = BlockRayTrace.getNearestHitResult(player, StateTypes.AIR, false);
         if (data != null) {
             BlockPlace blockPlace = new BlockPlace(player, hand, data.getPosition(), data.getClosestDirection().getFaceValue(), data.getClosestDirection(), held, data);
 
@@ -268,7 +194,7 @@ public class CheckManagerListener extends PacketListenerAbstract {
             // The offhand is unable to interact with blocks like this... try to stop some desync points before they happen
             if ((!player.isSneaking || onlyAir) && place.getHand() == InteractionHand.MAIN_HAND) {
                 Vector3i blockPosition = place.getBlockPosition();
-                BlockPlace blockPlace = new BlockPlace(player, place.getHand(), blockPosition, place.getFaceId(), place.getFace(), placedWith, getNearestHitResult(player, null, true));
+                BlockPlace blockPlace = new BlockPlace(player, place.getHand(), blockPosition, place.getFaceId(), place.getFace(), placedWith, BlockRayTrace.getNearestHitResult(player, null, true));
 
                 // Right-clicking a trapdoor/door/etc.
                 StateType placedAgainst = blockPlace.getPlacedAgainstMaterial();
@@ -308,7 +234,7 @@ public class CheckManagerListener extends PacketListenerAbstract {
                 placedWith = player.getInventory().getOffHand();
             }
 
-            BlockPlace blockPlace = new BlockPlace(player, place.getHand(), blockPosition, place.getFaceId(), face, placedWith, getNearestHitResult(player, null, true));
+            BlockPlace blockPlace = new BlockPlace(player, place.getHand(), blockPosition, place.getFaceId(), face, placedWith, BlockRayTrace.getNearestHitResult(player, null, true));
             // At this point, it is too late to cancel, so we can only flag, and cancel subsequent block places more aggressively
             if (!player.compensatedEntities.getSelf().inVehicle()) {
                 player.checkManager.onPostFlyingBlockPlace(blockPlace);
@@ -508,7 +434,7 @@ public class CheckManagerListener extends PacketListenerAbstract {
                 player.placeUseItemPackets.add(new BlockPlaceSnapshot(packet, player.isSneaking));
             } else {
                 // Anti-air place
-                BlockPlace blockPlace = new BlockPlace(player, packet.getHand(), packet.getBlockPosition(), packet.getFaceId(), packet.getFace(), placedWith, getNearestHitResult(player, null, true));
+                BlockPlace blockPlace = new BlockPlace(player, packet.getHand(), packet.getBlockPosition(), packet.getFaceId(), packet.getFace(), placedWith, BlockRayTrace.getNearestHitResult(player, null, true));
                 blockPlace.setCursor(packet.getCursorPosition());
 
                 if (PacketEvents.getAPI().getServerManager().getVersion().isNewerThanOrEquals(ServerVersion.V_1_11) && player.getClientVersion().isOlderThan(ClientVersion.V_1_11)) {
@@ -582,7 +508,7 @@ public class CheckManagerListener extends PacketListenerAbstract {
     }
 
     private static void placeBucket(GrimPlayer player, InteractionHand hand) {
-        HitData data = getNearestHitResult(player, null, true);
+        HitData data = BlockRayTrace.getNearestHitResult(player, null, true);
 
         if (data != null) {
             BlockPlace blockPlace = new BlockPlace(player, hand, data.getPosition(), data.getClosestDirection().getFaceValue(), data.getClosestDirection(), ItemStack.EMPTY, data);
@@ -748,7 +674,7 @@ public class CheckManagerListener extends PacketListenerAbstract {
     }
 
     private static void placeLilypad(GrimPlayer player, InteractionHand hand) {
-        HitData data = getNearestHitResult(player, null, true);
+        HitData data = BlockRayTrace.getNearestHitResult(player, null, true);
 
         if (data != null) {
             // A lilypad cannot replace a fluid
@@ -778,56 +704,6 @@ public class CheckManagerListener extends PacketListenerAbstract {
         }
     }
 
-    private static HitData getNearestHitResult(GrimPlayer player, StateType heldItem, boolean sourcesHaveHitbox) {
-        Vector3d startingPos = new Vector3d(player.x, player.y + player.getEyeHeight(), player.z);
-        Vector startingVec = new Vector(startingPos.getX(), startingPos.getY(), startingPos.getZ());
-        Ray trace = new Ray(player, startingPos.getX(), startingPos.getY(), startingPos.getZ(), player.xRot, player.yRot);
-        final double distance = player.compensatedEntities.getSelf().getAttributeValue(Attributes.PLAYER_BLOCK_INTERACTION_RANGE);
-        Vector endVec = trace.getPointAtDistance(distance);
-        Vector3d endPos = new Vector3d(endVec.getX(), endVec.getY(), endVec.getZ());
-
-        return traverseBlocks(player, startingPos, endPos, (block, vector3i) -> {
-            CollisionBox data = HitboxData.getBlockHitbox(player, heldItem, player.getClientVersion(), block, vector3i.getX(), vector3i.getY(), vector3i.getZ());
-            List<SimpleCollisionBox> boxes = new ArrayList<>();
-            data.downCast(boxes);
-
-            double bestHitResult = Double.MAX_VALUE;
-            Vector bestHitLoc = null;
-            BlockFace bestFace = null;
-
-            for (SimpleCollisionBox box : boxes) {
-                Pair<Vector, BlockFace> intercept = ReachUtils.calculateIntercept(box, trace.getOrigin(), trace.getPointAtDistance(distance));
-                if (intercept.getFirst() == null) continue; // No intercept
-
-                Vector hitLoc = intercept.getFirst();
-
-                if (hitLoc.distanceSquared(startingVec) < bestHitResult) {
-                    bestHitResult = hitLoc.distanceSquared(startingVec);
-                    bestHitLoc = hitLoc;
-                    bestFace = intercept.getSecond();
-                }
-            }
-            if (bestHitLoc != null) {
-                return new HitData(vector3i, bestHitLoc, bestFace, block);
-            }
-
-            if (sourcesHaveHitbox &&
-                    (player.compensatedWorld.isWaterSourceBlock(vector3i.getX(), vector3i.getY(), vector3i.getZ())
-                            || player.compensatedWorld.getLavaFluidLevelAt(vector3i.getX(), vector3i.getY(), vector3i.getZ()) == (8 / 9f))) {
-                double waterHeight = player.compensatedWorld.getFluidLevelAt(vector3i.getX(), vector3i.getY(), vector3i.getZ());
-                SimpleCollisionBox box = new SimpleCollisionBox(vector3i.getX(), vector3i.getY(), vector3i.getZ(), vector3i.getX() + 1, vector3i.getY() + waterHeight, vector3i.getZ() + 1);
-
-                Pair<Vector, BlockFace> intercept = ReachUtils.calculateIntercept(box, trace.getOrigin(), trace.getPointAtDistance(distance));
-
-                if (intercept.getFirst() != null) {
-                    return new HitData(vector3i, intercept.getFirst(), intercept.getSecond(), block);
-                }
-            }
-
-            return null;
-        });
-    }
-
     @Override
     public void onPacketSend(PacketSendEvent event) {
         if (event.getConnectionState() != ConnectionState.PLAY) return;

src/main/java/ac/grim/grimac/predictionengine/PointThreeEstimator.java

@@ -1,5 +1,6 @@
 package ac.grim.grimac.predictionengine;
 
+import ac.grim.grimac.checks.impl.combat.Reach;
 import ac.grim.grimac.player.GrimPlayer;
 import ac.grim.grimac.predictionengine.predictions.PredictionEngine;
 import ac.grim.grimac.utils.collisions.CollisionData;
@@ -16,6 +17,7 @@ import com.github.retrooper.packetevents.protocol.world.states.WrappedBlockState
 import com.github.retrooper.packetevents.protocol.world.states.defaulttags.BlockTags;
 import com.github.retrooper.packetevents.protocol.world.states.type.StateType;
 import com.github.retrooper.packetevents.protocol.world.states.type.StateTypes;
+import com.github.retrooper.packetevents.util.Vector3i;
 import lombok.Getter;
 import lombok.Setter;
 import org.bukkit.util.Vector;
@@ -151,6 +153,8 @@ public class PointThreeEstimator {
             isNearFluid = true;
         }
 
+        player.checkManager.getPacketCheck(Reach.class).handleBlockChange(new Vector3i(x, y, z), state);
+
         if (pointThreeBox.isIntersected(new SimpleCollisionBox(x, y, z))) {
             // https://github.com/MWHunter/Grim/issues/613
             int controllingEntityId = player.compensatedEntities.getSelf().inVehicle() ? player.getRidingVehicleId() : player.entityID;

src/main/java/ac/grim/grimac/utils/nmsutil/BlockRayTrace.java

@@ -0,0 +1,166 @@
+package ac.grim.grimac.utils.nmsutil;
+
+import ac.grim.grimac.player.GrimPlayer;
+import ac.grim.grimac.utils.collisions.HitboxData;
+import ac.grim.grimac.utils.collisions.datatypes.CollisionBox;
+import ac.grim.grimac.utils.collisions.datatypes.SimpleCollisionBox;
+import ac.grim.grimac.utils.data.HitData;
+import ac.grim.grimac.utils.data.Pair;
+import ac.grim.grimac.utils.math.GrimMath;
+import com.github.retrooper.packetevents.protocol.attribute.Attributes;
+import com.github.retrooper.packetevents.protocol.world.BlockFace;
+import com.github.retrooper.packetevents.protocol.world.states.WrappedBlockState;
+import com.github.retrooper.packetevents.protocol.world.states.type.StateType;
+import com.github.retrooper.packetevents.util.Vector3d;
+import com.github.retrooper.packetevents.util.Vector3i;
+import org.bukkit.util.Vector;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.BiFunction;
+
+public class BlockRayTrace {
+
+    // Copied from MCP...
+    // Returns null if there isn't anything.
+    //
+    // I do have to admit that I'm starting to like bifunctions/new java 8 things more than I originally did.
+    // although I still don't understand Mojang's obsession with streams in some of the hottest methods... that kills performance
+    public static HitData traverseBlocks(GrimPlayer player, Vector3d start, Vector3d end, BiFunction<WrappedBlockState, Vector3i, HitData> predicate) {
+        // I guess go back by the collision epsilon?
+        double endX = GrimMath.lerp(-1.0E-7D, end.x, start.x);
+        double endY = GrimMath.lerp(-1.0E-7D, end.y, start.y);
+        double endZ = GrimMath.lerp(-1.0E-7D, end.z, start.z);
+        double startX = GrimMath.lerp(-1.0E-7D, start.x, end.x);
+        double startY = GrimMath.lerp(-1.0E-7D, start.y, end.y);
+        double startZ = GrimMath.lerp(-1.0E-7D, start.z, end.z);
+        int floorStartX = GrimMath.floor(startX);
+        int floorStartY = GrimMath.floor(startY);
+        int floorStartZ = GrimMath.floor(startZ);
+
+
+        if (start.equals(end)) return null;
+
+        WrappedBlockState state = player.compensatedWorld.getWrappedBlockStateAt(floorStartX, floorStartY, floorStartZ);
+        HitData apply = predicate.apply(state, new Vector3i(floorStartX, floorStartY, floorStartZ));
+
+        if (apply != null) {
+            return apply;
+        }
+
+        double xDiff = endX - startX;
+        double yDiff = endY - startY;
+        double zDiff = endZ - startZ;
+        double xSign = Math.signum(xDiff);
+        double ySign = Math.signum(yDiff);
+        double zSign = Math.signum(zDiff);
+
+        double posXInverse = xSign == 0 ? Double.MAX_VALUE : xSign / xDiff;
+        double posYInverse = ySign == 0 ? Double.MAX_VALUE : ySign / yDiff;
+        double posZInverse = zSign == 0 ? Double.MAX_VALUE : zSign / zDiff;
+
+        double tMaxX = posXInverse * (xSign > 0 ? 1.0D - GrimMath.frac(startX) : GrimMath.frac(startX));
+        double tMaxY = posYInverse * (ySign > 0 ? 1.0D - GrimMath.frac(startY) : GrimMath.frac(startY));
+        double tMaxZ = posZInverse * (zSign > 0 ? 1.0D - GrimMath.frac(startZ) : GrimMath.frac(startZ));
+
+        // tMax represents the maximum distance along each axis before crossing a block boundary
+        // The loop continues until the ray has crossed a block boundary along all axes
+        while (tMaxX <= 1.0D || tMaxY <= 1.0D || tMaxZ <= 1.0D) {
+            if (tMaxX < tMaxY) {
+                if (tMaxX < tMaxZ) {
+                    floorStartX += xSign;
+                    tMaxX += posXInverse;
+                } else {
+                    floorStartZ += zSign;
+                    tMaxZ += posZInverse;
+                }
+            } else if (tMaxY < tMaxZ) {
+                floorStartY += ySign;
+                tMaxY += posYInverse;
+            } else {
+                floorStartZ += zSign;
+                tMaxZ += posZInverse;
+            }
+
+            state = player.compensatedWorld.getWrappedBlockStateAt(floorStartX, floorStartY, floorStartZ);
+            apply = predicate.apply(state, new Vector3i(floorStartX, floorStartY, floorStartZ));
+
+            if (apply != null) {
+                return apply;
+            }
+        }
+
+        return null;
+    }
+
+    public static HitData getNearestHitResult(GrimPlayer player, StateType heldItem, boolean sourcesHaveHitbox) {
+        Vector3d startingPos = new Vector3d(player.x, player.y + player.getEyeHeight(), player.z);
+        Vector startingVec = new Vector(startingPos.getX(), startingPos.getY(), startingPos.getZ());
+        Ray trace = new Ray(player, startingPos.getX(), startingPos.getY(), startingPos.getZ(), player.xRot, player.yRot);
+        final double distance = player.compensatedEntities.getSelf().getAttributeValue(
+            Attributes.PLAYER_BLOCK_INTERACTION_RANGE);
+        Vector endVec = trace.getPointAtDistance(distance);
+        Vector3d endPos = new Vector3d(endVec.getX(), endVec.getY(), endVec.getZ());
+        return getTraverseResult(player, heldItem, startingPos, startingVec, trace, endPos, sourcesHaveHitbox, false, distance + 3);
+    }
+
+    @Nullable
+    public static HitData getNearestReachHitResult(GrimPlayer player, Vector eyePos, Vector lookVec, double currentDistance, double maxDistance) {
+        Vector3d startingPos = new Vector3d(eyePos.getX(), eyePos.getY(), eyePos.getZ());
+        Vector startingVec = new Vector(startingPos.getX(), startingPos.getY(), startingPos.getZ());
+        Ray trace = new Ray(eyePos, lookVec);
+        Vector endVec = trace.getPointAtDistance(maxDistance);
+        Vector3d endPos = new Vector3d(endVec.getX(), endVec.getY(), endVec.getZ());
+        return getTraverseResult(player, null, startingPos, startingVec, trace, endPos, false, true, currentDistance);
+    }
+
+    private static HitData getTraverseResult(GrimPlayer player, @Nullable StateType heldItem, Vector3d startingPos, Vector startingVec, Ray trace, Vector3d endPos, boolean sourcesHaveHitbox, boolean checkInside, double knownDistance) {
+        return traverseBlocks(player, startingPos, endPos, (block, vector3i) -> {
+            CollisionBox data = HitboxData.getBlockHitbox(player, heldItem, player.getClientVersion(), block, vector3i.getX(), vector3i.getY(), vector3i.getZ());
+            List<SimpleCollisionBox> boxes = new ArrayList<>();
+            data.downCast(boxes);
+
+            double bestHitResult = Double.MAX_VALUE;
+            Vector bestHitLoc = null;
+            BlockFace bestFace = null;
+
+            for (SimpleCollisionBox box : boxes) {
+                Pair<Vector, BlockFace> intercept = ReachUtils.calculateIntercept(box, trace.getOrigin(), trace.getPointAtDistance(knownDistance));
+                if (intercept.getFirst() == null) continue; // No intercept
+
+                Vector hitLoc = intercept.getFirst();
+
+                // If inside a block, return empty result for reach check (don't bother checking this?)
+                if (checkInside && ReachUtils.isVecInside(box, trace.getOrigin())) {
+                    return null;
+                }
+
+                if (hitLoc.distanceSquared(startingVec) < bestHitResult) {
+                    bestHitResult = hitLoc.distanceSquared(startingVec);
+                    bestHitLoc = hitLoc;
+                    bestFace = intercept.getSecond();
+                }
+            }
+
+            if (bestHitLoc != null) {
+                return new HitData(vector3i, bestHitLoc, bestFace, block);
+            }
+
+            if (sourcesHaveHitbox &&
+                    (player.compensatedWorld.isWaterSourceBlock(vector3i.getX(), vector3i.getY(), vector3i.getZ())
+                            || player.compensatedWorld.getLavaFluidLevelAt(vector3i.getX(), vector3i.getY(), vector3i.getZ()) == (8 / 9f))) {
+                double waterHeight = player.compensatedWorld.getFluidLevelAt(vector3i.getX(), vector3i.getY(), vector3i.getZ());
+                SimpleCollisionBox box = new SimpleCollisionBox(vector3i.getX(), vector3i.getY(), vector3i.getZ(), vector3i.getX() + 1, vector3i.getY() + waterHeight, vector3i.getZ() + 1);
+
+                Pair<Vector, BlockFace> intercept = ReachUtils.calculateIntercept(box, trace.getOrigin(), trace.getPointAtDistance(knownDistance));
+
+                if (intercept.getFirst() != null) {
+                    return new HitData(vector3i, intercept.getFirst(), intercept.getSecond(), block);
+                }
+            }
+
+            return null;
+        });
+    }
+}